Affleck runs a charity dubbed the Eastern Congo Initiative that works with women and children in the Democratic Republic of Congo, which has one of the highest mortality rates in the world with 15 percent of the country's children dying before their fifth birthday. This year, more than 7 million children -- mostly in Africa -- reportedly will die before hitting the age of 5.

“I have three children who fall into the vulnerable age range,” Affleck said in his remarks at the Child Survival Call to Action, a conference hosted by the government in collaboration with Ethiopia, India and UNICEF, as reported by ABC News. “I cannot imagine what it would’ve been like driving my wife to the hospital pregnant, about to give birth and thinking to myself, 'Well there’s a 15 percent chance that each of these children won’t live to be 5 years old.'”

“Much of the time saving a child’s life is as simple as ensuring kids sleep under bed nets to avoid malaria and that they receive nutritional supplements and that they have immediate access to health care," he said. "This could save millions of lives a year alone and would cost less than $30 a child.”

Clinton introduced Affleck before his remarks, saying she's known the actor for a long time.

"I have watched him start his own family with three beautiful children and a wife that makes it all work,” she quipped. “I have enjoyed him in person, I have enjoyed him on the screen, but I particularly admire his commitment.”

Affleck most recently directed the movie Argo, in which he also stars as a CIA specialist who concocts a wild, desperate and ingenious plan to extract from Iran a number of U.S. citizens stranded in the home of the Canadian ambassador: pretend that the Americans were actually members of a Canadian film crew. The movie, based on a true story, opens Oct. 12.

Affleck also recently teamed up with Matt Damon and The Office'sJohn Krasinski to host a fundraiser for Elizabeth Warren's Senate campaign in Massachusetts.